Carl De Souza/AFP/Getty Images (NAIROBI, Kenya) -- Gunfire and explosions could still be heard coming from inside the Westgate Mall in Nairobi on Monday afternoon, as the Kenyan military worked to capture the remaining al-Qaeda militants who have held some mall patrons hostage since Saturday.

Kenya's military says that most of the hostages have been rescued, with four more freed early on Monday, though the fate of some of the remaining hostages is not clear. At least 62 people were killed in the attack and 175 more injured. Military forces were in the process of clearing the mall on Sunday, and said that the first and second floors had been secured, with the attackers likely on the ground floor or in the basement.

Military helicopters buzzed over the mall on Monday morning, with the siege having lasted for nearly two full days. Reports indicate that there may be as many as 10 hostages still inside the mall.

An intelligence bulletin from the FBI and U.S. Department of Homeland Security says that the attack, which began in the late-morning on Saturday, was likely perpetrated by 10-15 terrorists wearing black tactical clothing and ski masks. The terrorists reportedly used explosive devices before shooting civilians.